Pressurizing device

ABSTRACT

A pressurizing device comprising a control mechanism ( 7 ) which maintains the opening of a communication passage ( 22   a ) which allows the fluid pressure mechanism ( 6 ) to communicate with the outside when the fluid pressure mechanism is connected by a connection mechanism ( 5 ) and closing the communication passage ( 22   a ) by detecting the flow of a fluid in the fluid pressure mechanism ( 6 ) when the fluid is pushed to the outside by the energization of an input shaft ( 3 ) when the connection by the connection mechanism ( 5 ) is released so as to isolate the fluid pressure mechanism ( 6 ) from the outside.

PRIORITY CLAIM

This patent application is a U.S. National Phase of InternationalApplication No. PCT/JP2005/015890, filed Aug. 31, 2005, which claimspriority to Japanese Patent Application No. 2005-136322, filed May 9,2005, the disclosures of which are incorporated herein by reference intheir entirety.

FIELD

The present disclosure relates to a pressure apparatus in whichhigh-speed movement and high-thrust pressurization are compatible on anoutput shaft.

BACKGROUND

The present disclosure relates to a pressure apparatus in whichhigh-speed movement and high-thrust pressurization are made compatiblein spite of the use of a motor having a small capacity by adding ahydraulic pressure mechanism which makes use of Pascal's principle, thatis, a booster mechanism to a screw feed type pressure apparatus drivenby a motor (see, for example, International Patent Publication No. WO02/055291).

As shown in FIG. 11, the pressure apparatus comprises a stationary part10, an output shaft 20 supported on the stationary part 10 to be madeslidable in an axial direction, an input shaft 30 supported on theoutput shaft 20 to be slidable coaxially with the output shaft 20, aball screw type drive mechanism 40, which causes a motor (not shown) todirectly act the input shaft 30 in the axial direction, a connectingmechanism 50, in which the output shaft 20 and the input shaft 30 areconnected to each other by a connecting hook 501, a hydraulic pressuremechanism 60, which increases energization of the input shaft 30according to Pascal's principle to transmit the same to the output shaft20, and a control mechanism 70, which controls the operation of thehydraulic pressure mechanism 60.

A pressure receiving piston 201 is formed on the output shaft 20. Afirst fluid chamber A1 and a second fluid chamber A2, which arecompartmented in the axial direction by the pressure receiving piston201, are defined between the stationary part 10 and the output shaft 20.The first fluid chamber A1 and the second fluid chamber A2 arecommunicated to each other by communication passages 201 a, which areformed on the pressure receiving piston 201. Accordingly, the pressurereceiving piston 201 and the output shaft 20 can freely slide relativeto the stationary part 10 without being little subjected to resistanceby a fluid filled in the both fluid chambers A1, A2. Consequently, theoutput shaft 20 can be moved at high speed by the drive mechanism 40 ina state of being connected to the input shaft 30 by the connectingmechanism 50.

A pressure applying piston 301 is formed on the input shaft 30. A thirdfluid chamber A3 pressurized by the pressure applying piston 301 isformed between the output shaft 20 and the input shaft 30. The thirdfluid chamber A3 is communicated to the second fluid chamber A2 bycommunication holes 202 a. Accordingly, by releasing connection by theconnecting mechanism 50 and closing the communication passages 201 a,the second fluid chamber A2 and the third fluid chamber A3 function asthe hydraulic pressure mechanism 60 capable of transmitting energizationof the input shaft 30 to the output shaft 20. A pressure applying areaof the pressure applying piston 301 is set to be considerably smallerthan a pressure receiving area of the pressure receiving piston 201.Therefore, energization of the input shaft 30 is increased according toPascal's principle to pressurize the output shaft 20 at high thrust. Inaddition, when the output shaft 20 is pressurized at high thrust, thefirst fluid chamber A1 is compressed by the pressure receiving piston201 to be increased in internal pressure. A pressure absorbing piston101 is provided in the first fluid chamber A1 to absorb an increase ininternal pressure.

The connecting mechanism 50 comprises the connecting hook 501 fixed toan upper surface of the input shaft 30, an engagement 502 providedconcavely on an upper surface of the output shaft 20, and a connectionhook return roller 503 fixed to an upper portion of the stationary part10. A pawl is formed on a turning end of the connecting hook 501. Asshown in FIG. 11, the pawl engages with the engagement 502 whereby theoutput shaft 20 and the input shaft 30 are connected to each other so asnot to make relative movements. In this connected state, the input shaft30 moves downward to thereby make the output shaft 20 move at highspeed. When the input shaft 30 is stopped in movement after high-speedmovement of the output shaft 20 to a predetermined position, forexample, a position just before a tip end of the output shaft 20 abutsagainst a pressurized object, the output shaft 20 is moved downwardly ofthe input shaft 30 under the influence of an inertial force to stop asshown in FIG. 12. Thereby, the connecting hook 501 is disengaged fromthe engagement 502 and falls inside due to the bias of a spring (notshown) provided about an axis of turning with the result that connectionof the output shaft 20 and the input shaft 30 is released. In addition,when the input shaft 30 returns to an uppermost end (FIG. 11), at whichthe input shaft 30 is disposed in its origin position, after a series ofpressurizing actions are terminated, the connecting hook 501 is returnedto a position, in which it engages with the engagement 502, by theconnection hook return roller 503 to restore connection of the outputshaft 20 and the input shaft 30.

The hydraulic pressure mechanism 60 comprises the control mechanism 70,which controls communication between an interior (the second fluidchamber A2 and the third fluid chamber A3) of the hydraulic pressuremechanism 60 and an outside (the first fluid chamber A1), that is,opening and closing of the communication passages 201 a to control theoperation of the hydraulic pressure mechanism 60. The control mechanism70 comprises a pin-shaped valve element 701 and an auxiliary valveelement 702. The valve elements 701 are supported slidably by supportholes 202 provided on the output shaft 20 and the auxiliary valveelements 702 are supported slidably by support shafts 203 provided onthe output shaft 20. When the output shaft 20 and the input shaft 30 areconnected to each other by the connecting mechanism 50 to make norelative movements, the valve elements 701 retreat so as to open thecommunication passages 201 a as shown in FIGS. 11 and 12 and theauxiliary valve elements 702 are caused by an attracting force providedby built-in magnets (not shown) to shut off communication between thesecond fluid chamber A2 and the third fluid chamber A3.

Connection by the connecting mechanism 50 is released and the inputshaft 30 is moved downward whereby the control mechanism 70 begins theoperation of the hydraulic pressure mechanism 60. Owing to downwardmovement of the input shaft 30, the pressure applying piston 301 raisesa hydraulic pressure in the third fluid chamber A3 closed by theauxiliary valve elements 702. As the hydraulic pressure in the thirdfluid chamber A3 rises, the valve elements 701 are pushed down to closethe communication passages 201 a. Further, when a hydraulic pressure inthe third fluid chamber A3 rises, the auxiliary valve elements 702 arepushed up to provide a communication between the second fluid chamber A2and the third fluid chamber A3. Thereby, as shown in FIG. 13, the inputshaft 30 provided with the pressure applying piston 301, which has asmall pressure applying area, and the output shaft 20 provided with thepressure receiving piston 201, which has a large pressure receivingarea, are connected hydraulically to each other to enable increasingenergization of the input shaft 30 according to Pascal's principle totransmit the same to the output shaft 20. In addition, the magnets builtin the auxiliary valve elements 702 are set in attracting force so thatafter the valve elements 701 closes the communication passages 201 a,the auxiliary valve elements 702 provide a communication between thesecond fluid chamber A2 and the third fluid chamber A3. Also, pins (notshown) are provided upright on upper surfaces of the auxiliary valveelements 702. When the output shaft 20 returns to its origin position,the pins abut against an upper lid body 102 of the stationary part 10and the auxiliary valve elements 702 are pushed down to an initialposition, in which a communication between the first fluid chamber A1and the second fluid chamber A2 is shut off.

In the case where the output shaft 20 in the pressure apparatus makeshigh-speed movement and high-thrust pressurization, the connectingmechanism 50 first connects between the output shaft 20 and the inputshaft 30 to move the input shaft 30 to a predetermined position at highspeed. Subsequently, the input shaft 30 is stopped in the predeterminedposition whereby the connecting hook 501 turns to release connection ofthe output shaft 20 and the input shaft 30 as shown in FIG. 12.Thereafter, when downward movement of the input shaft 30 is begun again,pressurization by the pressure applying piston 301 raises the internalpressure in the third fluid chamber A3. Owing to an increase in internalpressure in the third fluid chamber A3, the control mechanism 70operates to cause the valve elements 701 to close the communicationpassages 201 a and to cause the auxiliary valve elements 702 to providea communication between the second fluid chamber A2 and the third fluidchamber A3 as shown in FIG. 13. A fluid pushed out from the third fluidchamber A3 by the pressure applying piston 301 having a small pressureapplying area flows into the second fluid chamber A2 to push thepressure receiving piston 201, which has a large pressure receivingarea, thereby pressurizing the output shaft 20 at high thrust.

When high-thrust pressurization is terminated, a fluid compressed in thefirst fluid chamber A1 causes a reaction force from the pressureabsorbing piston 101 to push back the valve elements 701 to open thecommunication passages 201 a. Thereby, a fluid can move to the firstfluid chamber A1 from the second fluid chamber A2. Accordingly, bymoving the input shaft 30 upward, the output shaft 20 can be returned tothe origin position. When the output shaft 20 is returned to the originposition, the auxiliary valve elements 702 are pushed down to an initialposition, in which a communication between the second fluid chamber A2and the third fluid chamber A3 is shut off.

The pressure apparatus makes high-speed movement and high-thrustpressurization compatible in spite of the use of a motor having a smallcapacity, but involves the following problems.

Firstly, the auxiliary valve elements 702 provided in order to shut offa communication between the second fluid chamber A2 and the third fluidchamber A3 makes the control mechanism 70 complex in constructioncausing an increased risk of generation of a failure.

Secondly, there is a need of surely returning the output shaft 20 to theorigin position in order to return the auxiliary valve elements 702 toan initial position, in which a communication between the second fluidchamber A2 and the third fluid chamber A3 is shut off. Accordingly, inthe case where it is unnecessary to retreat the output shaft 20 so much,there is a need of returning the output shaft 20 to the origin position,for example, even when it suffices that a spacing between the outputshaft 20 and a pressurized object be not considerably large, with theresult that loss in time is caused.

Thirdly, the valve elements 701 are held by slide resistance between thevalve elements 701 and the support holes 202. When the slide resistancebecomes too large, there is a fear that at the time of switchover tohigh-thrust pressurization from high-speed movement the auxiliary valveelements 702 act prior to the valve elements 701 to be unable to closethe communication passages 201 a. Therefore, it is necessary to strictlycontrol the dimensional relationship between the valve elements 701 andthe support holes 202 at the time of manufacture.

Fourthly, while the valve elements 701 are pushed back by a hydraulicpressure in the first fluid chamber A1 after high-thrust pressurizationis terminated, the valve elements 701 are formed in a pin-shaped mannerto be inserted into the communication passages 201 a and small inpressure receiving area. Therefore, there is a fear that only thehydraulic pressure in the first fluid chamber A1 does not return thevalve elements 701 fully to the initial position. That is, thecommunication passages 201 a are incompletely opened and so there is apossibility that the output shaft 20 becomes later in returning, whichis accompanied by movement of a fluid to the first fluid chamber A1 fromthe second fluid chamber A2.

In view of the problems, the present disclosure constructs a controlmechanism which controls the operation of a hydraulic pressuremechanism, so as to make the control mechanism simple in constructionand to enable the control mechanism to surely operate while the controlmechanism is easy to manufacture. Also, a pressure apparatus is providedin which an output shaft is not necessarily returned to an originposition and a stroke of operation can be changed appropriately.

SUMMARY

The present disclosure describes several exemplary embodiments of thepresent invention.

One aspect of the present disclosure provides a pressure apparatus,comprising a) a stationary part; b) an output shaft supported on thestationary part to be slidable in an axial direction; c) an input shaftsupported on the output shaft to be slidable coaxially with the outputshaft; d) a drive mechanism capable of moving the input shaft in theaxial direction; e) a connecting mechanism capable of connecting theoutput shaft and the input shaft to each other so as to inhibit relativemovements; f) a hydraulic pressure mechanism which connects the outputshaft and the input shaft hydraulically to each other at all times andcan increase energization of the input shaft according to Pascal'sprinciple to transmit the same to the output shaft when the output shaftand the input shaft move relative to each other; and, g) a controlmechanism which maintains a communication passage for communicationbetween the hydraulic pressure mechanism and an outside, open whenconnection by the connecting mechanism is provided and detects flow whena fluid in the hydraulic pressure mechanism is pushed outside byenergization of the input shaft, to thereby close the communicationpassage to shut off the hydraulic pressure mechanism from an outsidewhen connection by the connecting mechanism is released.

Another aspect of the present disclosure provides a pressure apparatus,comprising a) a stationary part including a hollow cylinder body formedon both ends thereof in a direction of cylinder axis with a firstthrough-hole and a second through-hole; b) an output shaft including ahollow cylinder body supported slidably by the first through-hole andthe second through-hole and defining a first fluid chamber and a secondfluid chamber between the output shaft and the stationary part; c) apressure receiving piston formed on the output shaft to compartment thefirst fluid chamber and the second fluid chamber and provided with acommunication passage which provides a communication between the firstfluid chamber and the second fluid chamber; d) an input shaft slidablysupported on the output shaft to form a third fluid chamber which iscommunicated to the second fluid chamber at all times between the inputshaft and the output shaft; e) a pressure applying piston formed on theinput shaft to expand and contract the third fluid chamber as the inputshaft reciprocates, the pressure applying piston having a smallerpressure applying area than a pressure receiving area of the pressurereceiving piston; f) a drive mechanism capable of moving the input shaftin a slide direction; g) a connecting mechanism capable of connectingthe output shaft and the input shaft to each other so as to inhibitrelative movements; and, h) a control mechanism which maintains thecommunication passage open when connection by the connecting mechanismis provided and detects flow of a fluid which is pushed out into thesecond fluid chamber from the third fluid chamber by energization of theinput shaft to close the communication passage when connection by theconnecting mechanism is released.

A further aspect of the present disclosure provides a pressureapparatus, comprising a) a stationary part; b) an output shaft supportedon the stationary part to be slidable in an axial direction; c) an inputshaft supported on the output shaft to be slidable coaxially with theoutput shaft; d) a drive mechanism which has the input shaftdirect-acting in an axial direction; e) a connecting mechanism whichconnects the output shaft and the input shaft to each other so as toinhibit relative movements; and, f) a hydraulic pressure mechanism whichconnects the output shaft and the input shaft hydraulically to eachother and can increase energization of the input shaft according toPascal's principle to transmit the same to the output shaft when theoutput shaft and the input shaft move relative to each other, whereinflow, when a fluid in the hydraulic pressure mechanism is pushed outsideby relative movements of the output shaft and the input shaft, isdetected to thereby switch the hydraulic pressure mechanism over to anoperable state.

An additional aspect of the present disclosure provides a pressureapparatus, comprising a) a stationary part; b) an output shaft supportedon the stationary part to be slidable in an axial direction; c) an inputshaft supported on the output shaft to be slidable coaxially with theoutput shaft; d) a drive mechanism which has the input shaftdirect-acting in an axial direction; e) a connecting mechanism whichconnects the output shaft and the input shaft to each other so as toinhibit relative movements; and, f) a hydraulic pressure mechanism whichconnects the output shaft and the input shaft hydraulically to eachother and can increase energization of the input shaft according toPascal's principle to transmit the same to the output shaft when theoutput shaft and the input shaft move relative to each other, whereinthe hydraulic pressure mechanism is switched over to an operable statewhen a fluid in the hydraulic pressure mechanism is pushed outside byrelative movements of the output shaft and the input shaft.

With the pressure apparatus of the present disclosure, the output shaftand the input shaft are connected hydraulically to each other at alltimes and by detecting flow of a fluid generated as the output shaft andthe input shaft are moved relative to each other, the operation (anincrease in energization caused according to Pascal's principle) of thehydraulic pressure mechanism is begun. Therefore, unlike theconventional pressure apparatus, in which an internal pressure in thethird fluid chamber is raised with hydraulic connection of the outputshaft and the input shaft shut off whereby relative movements of theoutput shaft and the input shaft are detected and the operation of thehydraulic pressure mechanism is begun, it is unnecessary to provide anauxiliary valve element and to return the output shaft to the originposition in order to return an auxiliary valve element to an initialposition, in which release of the connection can be detected.Consequently, there is produced an excellent effect that the apparatuscan be made simple in construction and easy to manufacture. Also, it isnot required that the output shaft be made larger in operating strokethan needed in order to ensure the operation of the hydraulic pressuremechanism.

Since a push force of flow of a fluid actuates the hydraulic pressuremechanism, one exemplary embodiment of the pressure apparatus allows theswitchover to high-thrust pressurization without the use of externalpower, such as electricity or the like, and the apparatus can be simplyconstructed.

Since an input portion acted by a push force, which is provided by flowof a fluid, is provided on the control mechanism and the input portionis arranged in opposition to flow of a fluid, another exemplaryembodiment of the pressure apparatus makes it possible to further surelyoperate the control mechanism.

Since the input portion is exposed to a bottom surface of a recessarranged in opposition to flow of a fluid, a further exemplaryembodiment of the pressure apparatus provides a push force by flow of afluid acting strongly to enable operating the control mechanism.

Since an input portion acted by the push force, which is provided byflow of a fluid, is provided on the control mechanism and the inputportion is arranged at an end of a passage path of the flow, anadditional exemplary embodiment of the pressure apparatus allows bettercontrol to operate the control mechanism.

Since the input portion is exposed to a bottom surface of a recessformed at the end of the passage path of flow of a fluid, a furtherexemplary embodiment of the pressure apparatus provides a push force byflow of a fluid acting strongly to enable operating the controlmechanism further surely.

Since the valve element is provided with a closure portion, which iscaused by the action of the push force to abut against and cover anopening of the communication passage to close the communication passage,another exemplary embodiment of the pressure apparatus ensures that thecommunication passage is surely closed.

Since the closure portion is set to be larger in area than the opening,a further exemplary embodiment of the pressure apparatus provides that,when high-thrust pressurization is terminated, a fluid flowing into aninterior of the hydraulic pressure mechanism from outside (into thesecond fluid chamber from the first fluid chamber) surely pushes backthe valve element to enable opening the communication passage fully.

Since a surface of the closure portion, which covers the opening, isformed to be concave, another exemplary embodiment of the pressureapparatus provides that, when high-thrust pressurization is terminated,a fluid flowing into an interior of the hydraulic pressure mechanismfrom outside (into the second fluid chamber from the first fluidchamber) acts on the concave surface, which has a large pressurereceiving area, to push up the closure portion with a further largeforce, thus enabling further surely opening the communication passage.

Since the valve element is supported slidably on a support portionformed on the output shaft and slid by the push force to close thecommunication passage, an exemplary embodiment of the pressure apparatusensures that the apparatus is simple in construction and suffers lessfailure.

Since the control mechanism includes a holding member, which holds thevalve element so as to maintain the communication passage open until thevalve element is acted by a push force of a predetermined value or more,a further exemplary embodiment of the pressure apparatus ensures thatthe communication passage is not closed inadvertently to cause failurein operation.

Since the holding member comprises a magnet, an additional exemplaryembodiment of the pressure apparatus ensures that the holdingconstruction is simple as compared with the case where a spring or thelike is used and there is less fear of failure and failure in operation.

Since the input portion is formed integral with the valve element, afurther exemplary embodiment of the pressure apparatus provides that thecontrol mechanism is simple in construction and suffers less failure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing a pressure apparatus accordingto an exemplary embodiment in a state before an output shaft beginshigh-speed movement and taken along the line A-A as shown in FIG. 2;

FIG. 2 is a cross-sectional view showing the pressure apparatus of FIG.1 in a state before the output shaft begins high-speed movement andtaken along the line B-B as shown in FIG. 1;

FIG. 3 is a view showing the pressure apparatus according to oneexemplary embodiment in a state just after the output shaft terminateshigh-speed movement;

FIG. 4 is a view showing the pressure apparatus according to anexemplary embodiment in a state just after the output shaft beginshigh-thrust pressurization;

FIG. 5 is a view showing the pressure apparatus according to anexemplary embodiment in a state just after the output shaft terminateshigh-thrust pressurization;

FIG. 6 is a view illustrating the operation of a control mechanism inthe pressure apparatus according to an exemplary embodiment when theoutput shaft shifts to high-thrust pressurization from high-speedmovement;

FIG. 7 is a view showing a state of the pressure apparatus according toan exemplary embodiment when communication passages are opened after theoutput shaft terminates high-thrust pressurization;

FIG. 8 is a view showing flow of a fluid in the pressure apparatusaccording to an exemplary embodiment when an input shaft moves upwardtogether with the output shaft to return to an original state;

FIG. 9 is an enlarged view showing the pressure apparatus according toan exemplary embodiment in a state in which a connecting mechanismconnects the output shaft and the input shaft to each other;

FIG. 10 is an enlarged view showing the pressure apparatus according toan exemplary embodiment in a state in which the connecting mechanismreleases connection of the output shaft and the input shaft;

FIG. 11 is a cross-sectional view showing a conventional pressureapparatus in a state before an output shaft begins high-speed movement;

FIG. 12 is a cross-sectional view showing the conventional pressureapparatus in a state just after the output shaft terminates high-speedmovement; and

FIG. 13 is a cross-sectional view showing the conventional pressureapparatus in a state just after the output shaft terminates high-thrustpressurization.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

-   -   1: stationary part    -   2: output shaft    -   3: input shaft    -   4: drive mechanism    -   5: connecting mechanism    -   6: hydraulic pressure mechanism    -   7: control mechanism    -   8: pressure absorbing mechanism    -   11 a: first through-hole    -   11 b: second through-hole    -   22: pressure receiving piston    -   22 a: communication passage    -   32: pressure applying piston    -   511: stationary hook body (first connecting member)    -   52: turning hook    -   521: turning hook body (second connecting member)    -   71: valve element    -   711: input portion    -   712: closed portion    -   72: support portion    -   721 a: recess    -   722: magnet    -   73 a: passage path    -   A1: first fluid chamber    -   A2: second fluid chamber    -   A3: third fluid chamber    -   W: pressurized object

DETAILED DESCRIPTION

One exemplary embodiment of the present disclosure is described belowwith reference to the accompanying drawings.

FIGS. 1-10 are cross-sectional views showing an example of a pressureapparatus, in which the present disclosure is embodied. FIGS. 1 and 2are views showing a state before an output shaft 2 begins high-speedmovement, FIG. 1 being a view showing a cross section taken along theline A-A in FIG. 2, and FIG. 2 being a view showing a cross sectiontaken along the line B-B in FIG. 1. FIGS. 3-5 show a cross sectioncorresponding to FIG. 1, FIG. 3 being a view showing a state after theoutput shaft 2 terminates high-speed movement, FIG. 4 being a viewshowing a state just after the output shaft 2 begins high-thrustpressurization, and FIG. 5 being a view showing a state just after theoutput shaft 2 terminates high-thrust pressurization. FIG. 6 is a viewillustrating the operation of the control mechanism 7 when the outputshaft 2 shifts to high-thrust pressurization. FIG. 7 is a view showing astate when communication passages 22 a are opened after the output shaft2 terminates high-thrust pressurization, and FIG. 8 is a view showingflow of a fluid when an input shaft 3 moves upward together with theoutput shaft 2 and returns to an original state. FIGS. 9 and 10 areenlarged views showing a connecting mechanism 5, FIG. 9 showing a statein which the output shaft 2 and the input shaft 3 are connected to eachother by the connecting mechanism 5, and FIG. 10 showing a state inwhich connection of the output shaft 2 and the input shaft 3 isreleased.

In addition, an explanation will be given below referring to upward anddownward, and left and right directions in the drawings for the sake ofconvenience, but posture/sense of installation of the pressure apparatusis not limited thereby and the pressure apparatus may be installed in adifferent posture/sense from that in the following descriptions, forexample, in a horizontal direction.

As shown in FIGS. 1-5, the pressure apparatus according to one exemplaryembodiment comprises a stationary part 1, the output shaft 2 insertedthrough and supported on the stationary part 1 to be slidable in anaxial direction, the input shaft 3 inserted through and supported on theoutput shaft 2 to be slidable coaxially with the output shaft 2, a drivemechanism 4 capable of reciprocating the input shaft 3 in the axialdirection, the connecting mechanism 5 capable of connecting the outputshaft 2 and the input shaft 3 to each other so as to inhibit relativemovements, a hydraulic pressure mechanism 6, which hydraulicallyconnects the output shaft 2 and the input shaft 3 to each other at alltimes and can increase energization of the input shaft 3 according toPascal's principle to transmit the same to the output shaft 2 in astate, in which connection by the connecting mechanism 5 is released, acontrol mechanism 7, which controls communication between inside andoutside the hydraulic pressure mechanism 6, and a pressure absorbingmechanism 8 connected to the stationary part 1 to permit pressure in afluid chamber (first fluid chamber A1), which is compressed when theoutput shaft 2 is subjected to high-thrust pressurization, to release.

With the pressure apparatus, as shown in FIG. 3, the input shaft 3 isconnected to the output shaft 2 by the connecting mechanism 5 in amanner not to move relative thereto whereby the output shaft 2 can bemoved at high speed with low thrust immediately before the output shaft2 abuts against a pressurized object W. Also, as shown in FIG. 4, byreleasing connection by the connecting mechanism 5 and moving the inputshaft 3 relative to the output shaft 2, it is possible to pressurize theoutput shaft 2 at high thrust while at low speed. That is, it ispossible to exhibit substantially the same function as that of apressure apparatus, which performs low-thrust high-speed movement andlow-speed high-thrust pressurization and uses a motor of a largecapacity to realize high-speed/high-thrust.

While the function described above is the same as that of a conventionalpressure apparatus (FIGS. 11-13), the present pressure apparatusprovides the connecting mechanism 5 and the control mechanism 7 withthose features, which are not found in the conventional pressureapparatus. The construction and operation of the present pressureapparatus as well as the features will be described in detail.

(Stationary Part 1)

As shown in FIGS. 1 and 2, the stationary part 1 includes a stationarypart body 11 in the form of a hollow cylinder, a plurality of guide rods12 fixed to the stationary part body 11 to extend in a direction of acylinder axis (vertical direction in the figure) of the stationary partbody 11, and a plate-shaped bearing part 13 fixed to and supported onupper ends of the guide rods 12, and is mounted on a stationary side.

(Stationary Part Body 11)

The stationary part body 11 includes a cylinder body 111 having acircular-shaped inner cross section and being in the form of a straightpipe, and a first lid body 112 and a second lid body 113, which aremounted to cover openings at both upper and lower ends of the cylinderbody 111. The first lid body 112 and the second lid body 113 are formedwith a first through-hole 11 a and a second through-hole 11 b, whichsupport the output shaft 2 slidably. The first through-hole 11 a and thesecond through-hole 11 b are formed to be smaller in diameter than aninner peripheral diameter of the cylinder body 111, and have a pluralityof circumferential grooves engraved at intervals in the direction ofcylinder axis on inner peripheral surfaces thereof. A sealing materialformed of a resin and having a U-shaped cross section, and a slipmaterial formed of a metal are fitted into the respectivecircumferential grooves.

(Guide Rod 12)

The guide rods 12 are provided upright in plural to surround the secondthrough-hole 11 b on the second lid body 113 to extend upward. The guiderods 12 have upper ends thereof supporting and fixing the bearing part13 thereto and have intermediate portions thereof slidably supporting asliding part 23, which is mounted to an upper portion of the outputshaft 2, to guarantee smooth, vertical movements of the output shaft 2.

(Bearing Part 13)

The bearing part 13 is a plate-shaped member, a periphery of which isfixed to and supported on the guide rods 12, and a center of which isformed with a through-hole 13 a. A roller bearing 131 is mounted in thethrough-hole 13 a to rotatably support a ball screw 41, whichconstitutes the drive mechanism 4. A servomotor 43 as well as the ballscrew 41 is connected and fixed to the bearing part 13 as shown in FIG.2.

(Output Shaft 2)

The output shaft 2 includes an output shaft body 21 in the form of ahollow cylinder, an annular pressure receiving piston 22 formedintegrally on an axially intermediate portion of the output shaft body21 and provided with a plurality of communication passages 22 a, whichare formed to extend therethrough in the direction of cylinder axis, anda plate-shaped slide part 23 mounted to a rear end (upper end in thefigure) of the output shaft body 21 and formed centrally thereof with athrough-hole 23 a.

(Output Shaft Body 21)

As shown in FIGS. 4 and 5, the output shaft body 21 is an output member,a tip end 21 e of which is pushed against the pressurized object W toperform a pressure processing. The output shaft body 21 has an outerperipheral surface 21 a thereof supported slidably by the firstthrough-hole 11 a and the second through-hole 11 b and defines a firstfluid chamber A1 and a second fluid chamber A2 between the outerperipheral surface 21 a and an inner peripheral surface 11 c of thestationary part body 11 (the cylinder body 111). The first fluid chamberA1 and the second fluid chamber A2 are filled with a fluid (oil). Thefluid is sealed by a sealing material, which is fitted into innerperipheral surfaces of the first through-hole 11 a and the secondthrough-hole 11 b, not to leak outside the stationary part body 11. Inaddition, communication holes 21 d are formed on a side of the outputshaft body 21 above the pressure receiving piston 22 to provide acommunication between the second fluid chamber A2 and a third fluidchamber A3 described later. The communication holes 21 d are formed inplural to correspond to each of the plurality of the communicationpassages 22 a provided at predetermined intervals circumferentially ofthe pressure receiving piston 22.

(Pressure Receiving Piston 22)

The pressure receiving piston 22 is formed to project radially outwardlyof the outer peripheral surface 21 a of the output shaft body 21 and tohave its outer peripheral surface 22 b extending along the innerperipheral surface 11 c of the stationary part body 11, thuscompartmenting the first fluid chamber A1 and the second fluid chamberA2. A sealing material and a slip material are fitted onto the outerperipheral surface 22 b of the pressure receiving piston 22 to providefor sealing so that the fluid does not leak between the first fluidchamber A1 and the second fluid chamber A2 from contact surfaces of thestationary part body 11 and the pressure receiving piston 22. However,when the stationary part 1 and the output shaft 2 slide relative to eachother to slide the pressure receiving piston 22 vertically, thecommunication passages 22 a are left open whereby the fluid in the firstfluid chamber A1 and the second fluid chamber A2 can move therebetween.An inner peripheral surface 21 c of that portion of the output shaftbody 21, on which the pressure receiving piston 22 is formed, is smallerin diameter than an inner peripheral surface 21 b except the portion.

(Slide Part 23)

The slide part 23 is a plate-shaped body formed centrally thereof withthe through-hole 23 a and fixed to the upper end of the output shaftbody 21 by a bolt or the like. The through-hole 23 a is provided topermit the ball screw 41 and a stationary hook 51 of the connectingmechanism 5 fixed to the input shaft 3 to extend therethrough. A turninghook 52, which constitutes the connecting mechanism 5 together with thestationary hook 51, is fixed to an upper surface of the slide part 23. Aplurality of support holes 23 b, which support the plurality of guiderods 12 described above, respectively, slidably, are formed on aperipheral edge of the slide part 23 to extend therethrough. Inaddition, when the input shaft 3 moves upward after high-thrustpressurization is terminated, an upper end of the input shaft 3 abutsagainst a peripheral edge of the through-hole 23 a of the slide part 23to push up the output shaft 2.

(Input Shaft 3)

The input shaft 3 includes a cylindrical-shaped input shaft body 31 andan annular pressure applying piston 32 formed integral with an upperportion of the input shaft body 31.

(Input Shaft Body 31)

The input shaft body 31 is a cylindrical body extended through aninterior of the output shaft body 21. An outer peripheral surface 31 aof the input shaft body 31 is slidably supported on the inner peripheralsurface 21 c of the output shaft body 21 and an outer peripheral surface32 a of the pressure applying piston 32 formed integral therewith isslidably supported on the inner peripheral surface 21 b of the outputshaft body 21. Thereby, the input shaft 3 is made axially slidablerelative to the output shaft 2 and the third fluid chamber A3 is definedbetween the outer peripheral surface 31 a of the input shaft body 31 andthe inner peripheral surface 21 b of the output shaft body 21. Sealingmaterials and slip materials are fitted onto the inner peripheralsurface 21 c of the output shaft body 21 and the outer peripheralsurface 32 a of the pressure applying piston 32, thereby sealing thefluid in the third fluid chamber A3 and ensuring smooth sliding of theinput shaft body 31.

(Pressure Applying Piston 32)

The pressure applying piston 32 reciprocates the input shaft 3vertically relative to the output shaft 2 to thereby expand or compressthe third fluid chamber A3. The input shaft 3 is moved downward relativeto the output shaft 2 whereby the pressure applying piston 32 compressesthe third fluid chamber A3 to enable the fluid in the third fluidchamber A3 to be pushed into the second fluid chamber A2 from thecommunication holes 21 d. Since a pressure applying area of the pressureapplying piston 32 is set to be considerably small as compared with apressure receiving area of the pressure receiving piston 22,energization of the pressure applying piston 32 (the input shaft 3) isincreased according to Pascal's principle when transmitted to thepressure receiving piston 22 (the output shaft 2).

(Drive Mechanism 4)

The drive mechanism 4 includes the ball screw 41 rotationally supportedon the bearing part 13, a ball bush 42 fixed inside the input shaft body31 to combine with the ball screw 41, the servomotor 43 connected andfixed to the bearing part 13, and a belt 44 for transmission of adriving force of the servomotor 43 to the ball screw 41, and the inputshaft 3 is made axially movable.

(Ball Screw 41 and Ball Bush 42)

The ball screw 41 combines with the ball bush 42, which is fixed to theinput shaft 3, to constitute a rotation-direct acting conversionmechanism, which is rotationally driven by the servomotor 43 toreciprocate (direct act) the input shaft 3 axially. A grease supply unit421 for supplying of grease to the ball bush 42 is provided above theball bush 42. The ball bush 42 is arranged in a position offset from acenter of the input shaft body 31 so as not to rotate the input shaft 3together.

(Servomotor 43 and Belt 44)

The servomotor 43 is fixed to the bearing part 13 to enable the inputshaft 3 to reciprocate to stop in a preset optional position. The belt44 is a toothed belt wound around pulleys, respectively, mounted to theball screw 41 and the servomotor 43.

(Connecting Mechanism 5)

As shown in FIGS. 1-5, the connecting mechanism 5 includes thestationary hook 51 fixed to an upper surface of the input shaft 3, theturning hook 52 fixed to the upper surface of the slide part 23 toenable turning, and an engagement 53 fixed to the upper surface of theslide part 23 to maintain the turning hook 52 in a state of engagingwith the stationary hook 51. As shown in FIG. 9, the connectingmechanism 5 has the stationary hook 51 and the turning hook 52 engagingwith each other to enable connecting the output shaft 2 and the inputshaft 3 to each other so as to inhibit relative movements. Also, asshown in FIG. 10, the connecting mechanism 5 permits the turning hook 52to turn to enable releasing the connection.

(Stationary Hook 51 and Turning Hook 52)

The stationary hook 51 includes a stationary hook body 511, which issubstantially C-shaped and forms a first connecting member, and a returnpin 512 provided upright on an upper surface of the stationary hook body511. The turning hook 52 includes a turning hook body 521, which issubstantially C-shaped and forms a second connecting member, and asupport shaft 522, which fixes the turning hook body thereto to enableturning. The stationary hook body 511 and the turning hook body 521 arefixed so that C-shaped openings thereof face each other, a tip end ofthe return pin 512 is made engageable with an upper end 521 a of anopening of the turning hook body 521, and a lower surface 511 a of anupper end of the stationary hook body 511 is made engageable with alower end 521 b of the opening of the turning hook body 521 as shown inFIG. 9.

As shown in FIG. 9, the turning hook body 521 is formed on a backthereof with an engaged portion (recess) 521 c, with which an engagementball 531 of the engagement 53 engages in a state, in which thestationary hook 51 and the turning hook 52 engage with each other. Asshown in FIG. 10, a lower portion of the engaged portion 521 c is cutobliquely in order to restrict resistance generated when the engagementball 531 is caused to engage with the engaged portion 521 c from astate, in which engagement of the stationary hook body 511 and theturning hook body 521 is released, to a small magnitude. Thereby, whileconnection by the connecting mechanism 5 is not released unless a forcebeing large to some measure acts, the connection can be restored byapplication of a slight force.

(Engagement 53)

As shown in FIG. 9, the engagement 53 includes an engagement ball 531,which engages with the engaged portion 521 c in a state, in which thestationary hook 51 and the turning hook 52 engage with each other, tohold the same so that the turning hook 52 does not turn in an engagementreleasing direction, and a regulating bolt 533 for regulation of apushing force of a push member 532, with which the engagement ball 531is pushed elastically against the back of the turning hook body 521,that is, a holding force, which holds the turning hook 52 in a state ofengaging with the stationary hook 51. In addition, the pushing force ofthe push member 532 is regulated so that the engagement ball 531 is notdisengaged from the engaged portion 521 c unless a large reaction forceacts on the output shaft 2, even when the input shaft 3 is moveddownward from a state shown in FIG. 9.

(Action of Connecting Mechanism 5)

As described above, even when the input shaft 3 is moved downward froman initial state (FIG. 1), in which the stationary hook 51 and theturning hook 52 engage with each other, the connecting mechanism 5maintains a state, in which the output shaft 2 and the input shaft 3 areconnected to each other. Accordingly, the output shaft 2 together withthe input shaft 3 can move to a position shown in FIG. 3 at high speed.Here, when the output shaft 2 is caused to abut against the pressurizedobject W at high speed an impact thereby causes damage to thepressurized object W and the pressure apparatus itself in some cases sothat the output shaft is once stopped in a position shown in FIG. 3 andthen begins downward movement again to abut against the pressurizedobject slowly. In addition, the servomotor 43 is adopted as a drivesource for the input shaft 3 and there is no need for taking account ofa magnitude of an overstroke of an output shaft like the conventionalpressure apparatus, so that it is possible to readily and exactly set aposition of stoppage.

When energization by the input shaft 3 is given after the output shaft 2abuts against the pressurized object W a reaction force is generated onthe output shaft 2 to relatively push up the output shaft 2 in a reversedirection to a direction in which the input shaft 3 is moved. Owing tothe action of the reaction force on the output shaft 2 the lower end 521b of the turning hook body 521 fixed to the output shaft 2 is pusheddown by the upper end 511 a of the stationary hook body 511 fixed to theinput shaft 3. Thereby, the engagement ball 531 is disengaged from theengaged portion 521 c so that the turning hook body 521 turns as shownin FIG. 10 to have the opening thereof directed downward. Thereby,engagement of the stationary hook 51 and the turning hook 52 isautomatically released and the input shaft 3 is put in a state of beingmovable relative to the output shaft 2 as shown in FIG. 4. Conversely,when the state in which engagement is released, shown in FIG. 10, is tobe returned to the state of engagement shown in FIG. 9, the input shaft3 is moved upward. Then it suffices that the turning hook body 521 beturned in the reverse direction by having the tip end of the return pin512 pushing up the upper end 521 a of the turning hook body 521.

Accordingly, detecting that the output shaft 2 abuts against thepressurized object W the connecting mechanism 5 can automaticallyrelease connection of the output shaft 2 and the input shaft 3. Also,after the connecting mechanism 5 releases the connection the input shaft3 is moved upward to have the stationary hook 51, which is fixed to theupper end of the input shaft 3 abutting against the turning hook 52 ofthe output shaft 2 whereby the turning hook 52 turns in the reversedirection to enable automatically restoring connection of the outputshaft 2 and the input shaft 3.

(Hydraulic Pressure Mechanism 6)

The hydraulic pressure mechanism 6 is formed so that the second fluidchamber A2, which is defined by the inner peripheral surface 11 c of thestationary part body 11 and the outer peripheral surface 21 a of theoutput shaft body 21 to be compartmented above the pressure receivingpiston 22, and the third fluid chamber A3, which is defined by the inputshaft body 31 and the inner peripheral surface 21 b of the output shaftbody 21 to be formed below the pressure applying piston 32, arecommunicated to each other by the communication holes 21 d formed on theoutput shaft body 21 to connect the output shaft 2 and the input shaft 3hydraulically to each other at all times. As described above, thehydraulic pressure mechanism 6 is set so that a pressure applying areaof the pressure applying piston 32 which pressurizes the third fluidchamber A3, is set to be considerably small as compared with a pressurereceiving area of the pressure receiving piston 22. Accordingly, in astate in which connection by the connecting mechanism 5 is released,that is, a state, in which the output shaft 2 and the input shaft 3 aremovable relative to each other, energization of the pressure applyingpiston 32 (the input shaft 3) is increased according to Pascal'sprinciple to be transmitted to the pressure receiving piston 22 (theoutput shaft 2), thus enabling pressurizing a pressurized object Wagainst which the output shaft 2 abuts with high thrust.

Since the communication passages 22 a are formed on the pressurereceiving piston 22 to provide a communication between the first fluidchamber A1 and the second fluid chamber A2, however, a fluid filled inthe hydraulic pressure mechanism 6 (the second fluid chamber A2 and thethird fluid chamber A3) is only pushed outside the hydraulic pressuremechanism 6 (the first fluid chamber A1) unless the communicationpassages 22 a are closed, even when pressurization by the pressureapplying piston 32 is made, so that it is not possible to realizehigh-thrust pressurization according to Pascal's principle. Hereupon,the control mechanism 7 described later enables automatically openingand closing the communication passages 22 a according to a state ofconnection between the output shaft 2 and the input shaft 3.

(Control Mechanism 7)

The control mechanism 7 comprises a valve element 71, a support portion72, and a fluid path forming portion 73. When the output shaft 2 and theinput shaft 3 is connected to each other by the connecting mechanism 5,the valve element 71 is held in a position to maintain the communicationpassages 22 a in communication as shown in FIGS. 1-3. Thereby, as theoutput shaft 2 is moved at high speed, a fluid can be moved to thesecond fluid chamber A2 from the first fluid chamber A1. Also, whenconnection by the connecting mechanism 5 is released, the controlmechanism 7 detects flow, which is generated in the hydraulic pressuremechanism 6 when a liquid in the hydraulic pressure mechanism 6 ispushed outside by energization of the input shaft 3, to close thecommunication passages 22 a to shut off the hydraulic pressure mechanism6 from outside as shown in FIGS. 4-6. Thereby, high-thrustpressurization according to Pascal's principle is made possible.

(Valve Element 71)

The valve element 71 is actuated by the push force of the flow describedabove to close the communication passages 22 a and arranged inside thehydraulic pressure mechanism 6. As shown in FIG. 6, the valve element 71includes a shaft-shaped input portion 711 acted by the push force offlow and a plate-shaped closure portion 712 acted by the push forcewhich is applied on the input portion 711 to abut against and coveropenings of the communication passages 22 a from inside the hydraulicpressure mechanism 6 to close the communication passages 22 a. The inputportion 711 is supported slidably by a support hole 721 which is formedon the support portion 72 and a front end 711 a and a rear end 711 bthereof are exposed. The closure portion 712 is fixed to the front end711 a to be opposed to the communication passages 22 a. The closureportion 712 is set to be larger in area than the openings of thecommunication passages 22 a and a surface thereof opposed to theopenings, that is, a closed surface 712 a which covers the openings isformed to be concave.

(Support Portion 72 and Fluid Path Forming Portion 73)

The support portion 72 is provided integrally on the output shaft 2 andformed with the support hole 721 which is formed to extend through thesupport portion and to support the input portion 711 slidably. A recess721 a is formed around an opening of the support hole 721, to which therear end 711 b of the input portion 711 is exposed. The rear end 711 bof the input portion 711 is put in a state to be exposed to a bottomsurface of the recess 721 a. The fluid path forming portion 73 isprovided integrally on the output shaft 2 to define a passage path 73 aas indicated by alternate long and short dash lines in FIG. 6, throughwhich a fluid pushed out from the communication holes 21 d byenergization of the input shaft 3 is guided to be opposed to the rearend 711 b of the input portion 711. That is, the input portion 711 isarranged at that end of the passage path 73 a, against which flowstrikes, in a manner to be opposed to the flow. Also, a magnet 722 isprovided around an opening of the support hole 721 toward the front end711 a of the input portion 711. The magnet 722 is a holding member whichmagnetically attracts the closure portion 712 to hold the valve element71 so as to maintain the communication passages 22 a open. Theattracting force by the magnet 722 is set to release attraction when apush force generated by flow to have a predetermined value or more actson the valve element 71.

(Pressure Absorbing Mechanism 8)

The pressure absorbing mechanism 8 is one by which fluid pressuregenerated in the first fluid chamber A1 when the output shaft 2 issubjected to high-thrust pressurization is permitted to escape. As shownin FIG. 2, the pressure absorbing mechanism 8 comprises acylindrical-shaped chamber case 81 connected to the stationary part 1 bya first fluid pipe 81 a, a chamber piston 82, which compartments aninterior of the chamber case 81 into a fourth fluid chamber A4 and anair chamber A5 and is slidable in the direction of cylinder axis, an aircompressor 83 connected to the chamber case 81 by a second fluid pipe 81b and a switching valve 84 provided on an intermediate portion of thesecond fluid pipe 81 b to set the air chamber A5 to either of anatmosphere opened state and a state connected to the air compressor 83.

The fourth fluid chamber A4 is filled with a fluid (oil) andcommunicated to the first fluid chamber A1. The air chamber A5 is filledwith an air and connected to the air compressor 83. The switching valve84 opens the air chamber A5 to the atmosphere normally but switches theair chamber A5 to a state of connecting to the air compressor 83 whenhigh-thrust pressurization is terminated and driving of the servomotor43 is stopped. After the switching a high-pressure air is fed into theair chamber A5 to raise an internal pressure in the fourth fluid chamberA4 and the first fluid chamber A1 communicated thereto. This is becausethe internal pressure as raised pushes up the valve element 71 to openthe communication passages 22 a.

(Operations of Hydraulic Pressure Mechanism 6, Control Mechanism 7, andPressure Absorbing Mechanism 8)

As described above, even when the input shaft 3 is moved downward froman initial state (FIGS. 1 and 2) of being connected to the output shaft2 the valve element 71 causes the attracting force of the magnet 722 tomaintain the communication passages 22 a open so that the output shaft 2can be moved just ahead a position shown in FIG. 3 at high speed withoutencountering a large resistance.

When the output shaft 2 abuts against the pressurized object W and theinput shaft 3 is moved downward in a state in which connection by theconnecting mechanism 5 is released, as shown in FIG. 4, the input shaft3 and the output shaft 2 are moved relative to each other to push thefluid out from the third fluid chamber A3. The third fluid chamber A3 iscommunicated to the second fluid chamber A2, the first fluid chamber A1,and the fourth fluid chamber A4. Since the air chamber A5 on an oppositeside to the fourth fluid chamber A4 with the chamber piston 82therebetween is opened to the atmosphere, however, the fourth fluidchamber A4 is freely enlarged without resistance. Accordingly, a fluidis pushed out from the third fluid chamber A3 whereby flow of a fluiddirected toward the second fluid chamber A2 from the third fluid chamberA3, that is, flow of a fluid directed outside from within the hydraulicpressure mechanism 6 is generated.

As indicated by alternate long and short dash lines in FIG. 6 the flowis guided by the L-shaped passage path 73 a a discharge port of which isprovided to be directed downward to be directed toward the input portion711. Since the input portion 711 is arranged at the end of the passagepath 73 a in a manner to be opposed to the flow it is exerted directlyby the push force of the flow to be slid downward so that the closureportion 712 fixed to the front end 711 a closes and covers thecommunication passages 22 a. In addition, since the input portion 711 isexposed to the bottom surface of the recess 721 a, flow led to therecess 721 a acts strongly on the input portion 711. Thus, the hydraulicpressure mechanism 6 is shut off from outside and energization of theinput shaft 3 is increased according to Pascal's principle, thusenabling high-thrust pressurization on the output shaft 2.

When high-thrust pressurization is terminated and the servomotor 43stops the switching valve 84 operates interlocking therewith to permit ahigh-pressure air to be fed from the air compressor 83 to enlarge theair chamber A5. Thereby, the fourth fluid chamber A4 and the first fluidchamber A1 are compressed and the hydraulic pressure thereby pushes backthe closure portion 712 (the valve element 71) which closes thecommunication passages 22 a upward. In particular, the closure portion712 is set to be larger in area than the communication passages 22 a anda surface thereof, which covers the openings of the communicationpassages 22 a is formed to be concave so that the hydraulic pressureefficiently acts to surely push up the valve element 71. The valveelement 71 thus pushed up is attracted by the magnet 722 which isembedded in the support portion 72 to be held in a state of putting thecommunication passages 22 a in communication.

Thereafter, when the servomotor 43 is reversely driven to drive theinput shaft 3 upward the input shaft is moved until the upper end of theinput shaft 3 abuts against a stopper (a peripheral edge of thethrough-hole 23 a of the slide part 23) provided on the output shaft 2,that is, moved to a position just before high-thrust pressurization isbegun. In addition, since the pressure applying piston 32 is movedupward to enlarge the third fluid chamber A3, the fluid flows to bedrawn into the third fluid chamber A3 through the second fluid chamberA2 from the first fluid chamber A1 as shown in FIG. 7, but the flow isdirected to push up the valve element 71 as indicated by alternate longand short dash lines whereby the valve element 71 does not operate in aclosing direction.

When the servomotor 43 continues to be driven even after the upper endof the input shaft 3 abuts against the stopper provided on the outputshaft 2 the output shaft 2 is pushed up by the input shaft 3 to be movedupward. Since the communication passages 22 a provided on the pressurereceiving piston 22 are opened the output shaft 2 can be moved at highspeed without encountering a large resistance. In addition, since anupper portion of the input portion 711 is covered by the fluid pathforming portion 73 a fluid moving to the first fluid chamber A1 from thesecond fluid chamber A2 at high speed moves keeping away from the inputportion 711 as shown in FIG. 8. Accordingly, there is no fear that thecommunication passages 22 a are closed when the output shaft 2 isreturned to an original state.

(Operation of Pressure Apparatus According to One Exemplary Embodiment)

An explanation will be given below to an operation of the whole pressureapparatus according to one exemplary embodiment.

(High-Speed Movement of Output Shaft 2)

After a pressurized object W is set below the output shaft 2 in a stateshown in FIGS. 1 and 2 the servomotor 43 is rotationally driven to movethe input shaft 3 downward. Since the input shaft 3 is connected to theoutput shaft 2 by the connecting mechanism 5 and the communicationpassages 22 a of the pressure receiving piston 22 formed on the outputshaft 2 are opened the output shaft 2 is moved downward at high speedwhile a fluid moves to the second fluid chamber A2 from the first fluidchamber A1.

(Release of Connection by the Connecting Mechanism 5)

After the output shaft 2 stops high-speed movement just before abuttingagainst a pressurized object W as shown in FIG. 3 it begins downwardmovement again to abut against the pressurized object W whereby areaction force on the output shaft 2 is generated from the pressurizedobject W. Thereby, the turning hook body 521 is turned to be releasedfrom engagement with the stationary hook body 511 as shown in FIG. 10.That is, connection by the connecting mechanism 5 is released to bringabout a state in which the output shaft 2 and the input shaft 3 is mademovable vertically.

(Closure of Communication Passages 22 a—Switchover to a State, in whichHydraulic Pressure Mechanism 6 can Operate)

When the input shaft 3 is further energized in a state in which theoutput shaft 2 and the input shaft 3 is movable relative to each other afluid in the third fluid chamber A3 is pushed out by the pressureapplying piston 32. A push force by the fluid as pushed out causes thevalve element 71 of the control mechanism 7 to close the communicationpassages 22 a as shown in FIG. 6 to complete switchover to a state inwhich the hydraulic pressure mechanism 6 can operate as shown in FIG. 4.

(High-Thrust Pressurization of Output Shaft 2)

When the input shaft 3 is energized from a state shown in FIG. 4 theinput shaft 3 is further moved downward as shown in FIG. 5. Theenergizing force of the input shaft 3 is transmitted to the pressurereceiving piston 22 having a large pressure receiving area from thepressure applying piston 32 having a small pressure applying areathrough the fluid in the hydraulic pressure mechanism 6 as closed. Thatis, the energizing force of the input shaft 3 is increased according toPascal's principle and the output shaft 2 is subjected to high-thrustpressurization.

(Opening of Communication Passages 22 a)

When the servomotor 43 is stopped after high-thrust pressurization bythe output shaft 2 is terminated switchover by the switching valve 84 ismade interlocking therewith to cause a high-pressure air from the aircompressor 83 to pressurize the first fluid chamber A1. As shown in FIG.7, the fluid in the first fluid chamber A1 pushes up the valve element71 to a position in which the valve element is held by the magnet 722 toput the communication passages 22 a in communication.

(Return of Pressure Applying Piston 32—Restoration of Connection byConnecting Mechanism 5)

By reversely rotating the servomotor 43 in a state in which thecommunication passages 22 a are put in communication it is possible toreturn the pressure applying piston 32 (the input shaft 3) to a positionbefore high-thrust pressurization shown in FIG. 3 while introducing afluid into the third fluid chamber A3 from the first fluid chamber A1 asindicated by alternate long and short dash lines in FIG. 7. The inputshaft 3 is returned to a position before high-thrust pressurization tobring about a state in which the upper end of the input shaft 3 can pushup the output shaft 2 (the slide part 23) and connection of the outputshaft 2 and the input shaft 3 by the connecting mechanism 5 is restored.

(Return of Output Shaft 2)

By driving the servomotor 43 further from a state shown in FIG. 3, theinput shaft 3 pushes up the output shaft 2 to return the same to theinitial state shown in FIG. 1. In addition, since the communicationpassages 22 a ensures a communication between the first fluid chamber A1and the second fluid chamber A2 the output shaft 2 can return to itsoriginal position at high speed without encountering a large resistance.In this manner, a series of actions by the pressure apparatus accordingto one exemplary embodiment are terminated.

(Features of Pressure Apparatus According to One Exemplary Embodiment)

The pressure apparatus according to one exemplary embodiment has thefollowing features.

Firstly, the pressure apparatus has a feature that the output shaft 2and the input shaft 3 are connected hydraulically to each other at alltimes and release of connection of the output shaft 2 and the inputshaft 3 by the connecting mechanism 5 is detected according to flow of afluid generated by relative movements of the input shaft 3 and theoutput shaft 2 to begin an action of the hydraulic pressure mechanism 6(an increase in an energizing force according to Pascal's principle).Owing to the feature, it is unnecessary to provide an auxiliary valveelement which shuts off fluid connection of an output shaft and an inputshaft as in the conventional pressure apparatus shown in FIGS. 11-13 inorder to detect release of connection of the output shaft 2 and theinput shaft 3. Consequently, it is possible to make the pressureapparatus simple in apparatus construction and easy in manufacture.

Also, while it is necessary in the conventional pressure apparatus toreturn an output shaft to a home position (uppermost end) in order toreturn the same to an initial position in which an auxiliary valveelement can shuts off fluid connection of the output shaft and the inputshaft it is unnecessary in the present pressure apparatus to return theoutput shaft 2 to such position.

Secondly, the pressure apparatus has a feature that a push forceprovided by flow of a fluid generated by relative movements of the inputshaft 3 and the output shaft 2 drives the valve element 71 directly toclose the communication passages 22 a to switch the hydraulic pressuremechanism 6 over to a state enabling an operation. Owing to the featurewhen the input shaft 3 and the output shaft 2 move relative to eachother switchover to high-thrust pressurization can be made rapidlywithout the use of external power such as electricity or the like.

Thirdly, the pressure apparatus has a feature that the input portion 711acted by a driving force (push force) of the valve element 71 isarranged at the end of the passage path 73 a in a manner to be opposedto flow of a fluid. Owing to the feature, flow of a fluid pushed outfrom the third fluid chamber A3 strikes frontally against the inputportion 711, thus enabling surely closing the communication passages 22a.

Fourthly, the pressure apparatus has a feature that the input portion711 is exposed to the bottom surface of the recess formed at the end ofthe passage path 73 a in a manner to be opposed to flow of a fluid.Owing to the feature, a push force provided by flow of a fluid actsstrongly on the input portion 711, thus enabling further surely closingthe communication passages 22 a.

Fifthly, the pressure apparatus has a feature that the plate-shapedclosure portion 712 is provided on the valve element 71 and caused bythe action of a push force provided by flow of a fluid to abut againstthe pressure receiving piston 22 in a manner to cover the openings ofthe communication passages 22 a to surely close the communicationpassages 22 a.

Sixthly, the pressure apparatus has a feature that the closure portion712 is set to be larger in area than the openings of the communicationpassages 22 a. Owing to the feature, when high-thrust pressurization ismade, a fluid in the hydraulic pressure mechanism 6 can strongly closethe closure portion 712 and when high-thrust pressurization isterminated, a push force provided by a fluid in the first fluid chamberA1 surely pushes back the closure portion 712, thus enabling surelyopening the communication passages 22 a.

Seventhly, the pressure apparatus has a feature that a closing surfaceof the closure portion 712, which covers the openings of thecommunication passages 22 a, is formed to be concave to have a furtherlarge pressure receiving area. Owing to the feature, when high-thrustpressurization is terminated a push force provided by a fluid in thefirst fluid chamber A1 acts on the concave surface having a largepressure receiving area to surely push back the closure portion 712 witha further large force, thus enabling further surely opening thecommunication passages 22 a.

Eighthly, the pressure apparatus has a feature that the valve element 71is supported slidably by the support portion 72 formed on the outputshaft 2 and caused by a push force provided by flow of a fluid to slideto close the communication passages 22 a. Owing to the feature, thevalve element 71 is simple in structure and can do with less trouble.

Ninthly, the pressure apparatus has a feature that the magnet isprovided as a holding member, which holds the valve element 71 so as tomaintain the communication passages 22 a open until the valve element 71is acted by a push force of a predetermined value or more. Owing to thefeature, it is possible to prevent the communication passages 22 a frombeing closed inadvertently to cause failure in operation and to do withless fear that the holding member itself suffers failure.

Tenthly, the pressure apparatus has a feature that when the input shaft3 is connected to the output shaft 2 so as to inhibit relative movementsand moved downward it is possible to automatically release connection ofthe output shaft 2 and the input shaft 3 detecting that the output shaft2 abuts against the pressurized object W. Owing to the feature, itsuffices that time required for newly setting a position, in whichhigh-thrust pressurization is begun, be short, and an arrangement can beexchanged in a short period of time even in the case where a point ofswitchover is moved in exchanging a pressurized object W.

Eleventhly, the pressure apparatus has a feature that detecting that areaction force is generated on the output shaft 2 in a reverse directionto a direction of movement while the input shaft 3 moves the outputshaft 2 downward connection of the output shaft 2 and the input shaft 3is automatically released. Owing to the feature, even in the case wherethe output shaft 2 is abnormally locked while the input shaft 3 moves athigh speed, connection of the output shaft 2 and the input shaft 3 isreleased at that point of time so that it is possible to avoid asituation where the connecting mechanism 5 is applied by a large load tobreak.

Twelfthly, the pressure apparatus has a feature that when a reactionforce is generated on the output shaft 2 in a reverse (upward) directionto a direction of movement while the input shaft 3 moves the outputshaft 2 downward connection by the connecting mechanism 5 isautomatically released by the action of the reaction force. Owing to thefeature, there is no need of providing a drive source for release ofconnection so that it is possible to avoid complication of theapparatus.

Thirteenthly, the pressure apparatus has a feature that when a reactionforce is generated on the output shaft 2 in a reverse direction to adirection of movement the stationary hook 51 itself makes use of thereaction force to turn the turning hook 52 to release connection by theconnecting mechanism 5. Owing to the feature, there is no need ofseparately providing a part for turning of the turning hook 52, thusenabling making the number of parts small.

Fourteenthly, the pressure apparatus has a feature that it is possibleto regulate a holding force, which holds the turning hook 52 in a stateof engaging with the stationary hook 51. Owing to the feature, it ispossible to finely regulate a preload applied on a pressurized object Wfrom the output shaft 2 before high-thrust pressurization is begun,depending upon the pressurized object W.

Fifteenthly, the pressure apparatus has a feature that by returning theinput shaft 3 to a position before high-thrust pressurization from astate, in which connection by the connecting mechanism 5 is released thestationary hook 51 engages with the turning hook 52 to automaticallyrestore connection of the output shaft 2 and the input shaft 3 by theconnecting mechanism 5. Owing to the feature, there is no need of movingthe output shaft 2 to the uppermost end in order to restore connectionof the output shaft 2 and the input shaft 3 by the connecting mechanism5.

Sixteenthly, the pressure apparatus has a feature that by returning(upwardly moving) the input shaft 3 from a state in which connection bythe connecting mechanism 5 is released the stationary hook 51 fixed tothe upper end of the input shaft 3 abuts against the turning hook 52 onthe output shaft 2 so that the turning hook 52 is turned in a reversedirection to automatically restore connection of the output shaft 2 andthe input shaft 3. Owing to the feature, there is no need of providing adrive source for restoration of connection, so that it is possible toavoid complication of the apparatus.

Modification of the Exemplary Embodiment

While according to the exemplary embodiment, connection by theconnecting mechanism 5 is released detecting that the output shaft 2itself abuts against a pressurized object W, this is not limitative butconnection by the connecting mechanism 5 may be released detecting thata member mounted to the output shaft 2 abuts against another member. Forexample, the case where a moving die of an injection molding machine ismounted to the output shaft 2 and the moving die abuts against astationary die at the time of closing, and the case where a push die ofa press machine is mounted to the output shaft 2 and the push die abutsagainst a bearing die or a press worked material set on the bearing diemay be detected.

While according to the exemplary embodiment it is detected on the basisof a reaction force, which the pressurized object W acts on the outputshaft 2 that the output shaft 2 abuts against a pressurized object Wother detection methods may be used. For example, a load sensor, such asload cell, etc., or an acceleration sensor may be provided on the outputshaft 2 and it may be detected on the basis of a change in an outputsignal from the sensor that the output shaft 2 moving at high speedabuts against a pressurized object W.

While according to the exemplary embodiment, a reaction force acted onthe output shaft 2 from the pressurized object W is made use of torelease connection by the connecting mechanism 5, the connection may bereleased by energy supplied from outside according to a change in anoutput signal from the sensor described above. For example, theconnection may be released by an electrically-driven orpneumatically-driven actuator.

While according to the exemplary embodiment, the combination of thestationary hook 51 provided on the input shaft 3 and the turning hook 52provided on the output shaft 2 is adopted as the connecting mechanism 5for connection of the output shaft 2 and the input shaft 3, otherconstructions can be adopted provided that the output shaft 2 and theinput shaft 3 can be connected to each other so as not to move relativeto each other.

While according to the exemplary embodiment, in order to relieve animpact when the output shaft 2 abuts against the pressurized object W,the input shaft 3 is once stopped just before abutting and then beginsmovement again, abutting may be of course made decreasing the movingspeed without complete stoppage.

Besides, of course, the present disclosure is not limited to theexemplary embodiment but various modifications can be made within ascope without departing from the spirit of the invention.

All patents, patent applications and publications referred to herein areincorporated by reference in their entirety.

1. A pressure apparatus, comprising: a) a stationary part; b) an outputshaft supported on the stationary part to be slidable in an axialdirection; c) an input shaft supported on the output shaft to beslidable coaxially with the output shaft; d) a drive mechanism capableof moving the input shaft in the axial direction; e) a connectingmechanism capable of connecting the output shaft and the input shaft toeach other so as to inhibit relative movements; f) a hydraulic pressuremechanism which connects the output shaft and the input shafthydraulically to each other at all times and can increase energizationof the input shaft according to Pascal's principle to transmit the sameto the output shaft when the output shaft and the input shaft moverelative to each other; and, g) a control mechanism which maintains acommunication passage for communication between the hydraulic pressuremechanism and an outside, open when connection by the connectingmechanism is provided and detects flow when a fluid in the hydraulicpressure mechanism is pushed outside by energization of the input shaft,to thereby close the communication passage to shut off the hydraulicpressure mechanism from an outside when connection by the connectingmechanism is released.
 2. A pressure apparatus, comprising: a) astationary part including a hollow cylinder body formed on both endsthereof in a direction of cylinder axis with a first through-hole and asecond through-hole; b) an output shaft including a hollow cylinder bodysupported slidably by the first through-hole and the second through-holeand defining a first fluid chamber and a second fluid chamber betweenthe output shaft and the stationary part; c) a pressure receiving pistonformed on the output shaft to compartment the first fluid chamber andthe second fluid chamber and provided with a communication passage whichprovides a communication between the first fluid chamber and the secondfluid chamber; d) an input shaft supported slidably on the output shaftto form a third fluid chamber which is communicated to the second fluidchamber at all times between the input shaft and the output shaft; e) apressure applying piston formed on the input shaft to expand andcontract the third fluid chamber as the input shaft reciprocates, thepressure applying piston having a smaller pressure applying area than apressure receiving area of the pressure receiving pistons; f) a drivemechanism capable of moving the input shaft in a slide direction; g) aconnecting mechanism capable of connecting the output shaft and theinput shaft to each other so as to inhibit relative movements; and, h) acontrol mechanism which maintains the communication passage open whenconnection by the connecting mechanism is provided and detects flow of afluid which is pushed out into the second fluid chamber from the thirdfluid chamber by energization of the input shaft to close thecommunication passage when connection by the connecting mechanism isreleased.
 3. The pressure apparatus of claim 1, wherein the controlmechanism further comprises a valve element which is operated by a pushforce of the flow to close the communication passage.
 4. The pressureapparatus of claim 3, wherein the control mechanism further comprises aninput portion which is acted by the push force to drive the valveelement and the input portion is arranged in opposition to the flow. 5.The pressure apparatus of claim 4, wherein the input portion is exposedto a bottom surface of a recess arranged in opposition to the flow. 6.The pressure apparatus of claim 3, wherein the control mechanism furthercomprises an input portions which is acted by the push force to drivethe valve element and the input portion is arranged at an end of apassage path of the flow.
 7. The pressure apparatus of claim 6, whereinthe input portion is exposed to a bottom surface of a recess formed atthe end.
 8. The pressure apparatus of claim 4, wherein the valve elementfurther comprises a closure portion which is caused by the action of thepush force to abut against and cover an opening of the communicationpassage to close the communication passage.
 9. The pressure apparatus ofclaim 8, wherein the closure portion is set to be larger in area thanthe opening.
 10. The pressure apparatus of claim 8, wherein a surface ofthe closure portion which covers the opening is formed to be concave.11. The pressure apparatus of claim 4, wherein the valve element isslidably supported on a support portion formed on the output shaft andslid by the push force to close the communication passage.
 12. Thepressure apparatus of claim 3, wherein the control mechanism furthercomprises a holding member which holds the valve element so as tomaintain the communication passage open until the valve element is actedby a push force of a predetermined value or more.
 13. The pressureapparatus of claim 12, wherein the holding member comprises a magnet.14. The pressure apparatus of claim 4, wherein the input portion isformed integral with the valve element.
 15. A pressure apparatus,comprising: a) a stationary part; b) an output shaft supported on thestationary part to be slidable in an axial directions; c) an input shaftsupported on the output shaft to be slidable coaxially with the outputshaft; d) a drive mechanism which has the input shaft direct-acting inan axial direction; e) a connecting mechanism which connects the outputshaft and the input shaft to each other so as to inhibit relativemovements; and, f) a hydraulic pressure mechanism which connects theoutput shaft and the input shaft hydraulically to each other and canincrease energization of the input shaft according to Pascal's principleto transmit the same to the output shaft when the output shaft and theinput shaft move relative to each other; and, wherein flow, when a fluidin the hydraulic pressure mechanism is pushed outside by relativemovements of the output shaft and the input shaft, is detected tothereby switch the hydraulic pressure mechanism over to an operablestate.
 16. A pressure apparatus, comprising: a) a stationary part; b) anoutput shaft supported on the stationary part to be slidable in an axialdirection; c) an input shaft supported on the output shaft to beslidable coaxially with the output shaft; d) a drive mechanism which hasthe input shaft direct-acting in an axial direction; e) a connectingmechanism which connects the output shaft and the input shaft to eachother so as to inhibit relative movements; and, f) a hydraulic pressuremechanisms which connects the output shaft and the input shafthydraulically to each other and can increase energization of the inputshaft according to Pascal's principle to transmit the same to the outputshaft when the output shaft and the input shaft move relative to eachother, wherein the hydraulic pressure mechanism is switched over to anoperable state when a fluid in the hydraulic pressure mechanism ispushed outside by relative movements of the output shaft and the inputshaft.
 17. The pressure apparatus of claim 2, wherein the controlmechanism further comprises a valve element which is operated by a pushforce of the flow to close the communication passage.